Authors: TS Singh, B Bello, OD Mabe, K Renton, MF Jeebhay

Source: Ann.Occup.Hyg.2010, 54 (3): 299-308


It is well known that dental units provide an environment conducive to the rapid proliferation of microorganisms. A previous study investigating DUWLs in South African dental clinics showed high levels of Legionella, a gram negative bacterium. These bacteria produce endotoxin during bacterial growth phase and upon lysis. During dental procedures with high-speed dental instruments, aerosols are generated and the particles remain airborne for many hours. Detectable levels of endotoxin have been reported in air samples obtained from dental institutions with some as high as 625 EU/m3 and some low. Of potentially greater significance is the chronic low dose exposure of those involved in the dental profession. Chronic endotoxin inhalation represents an occupational respiratory hazard to this group of professionals.

This information would be useful in setting priorities for the reduction of endotoxin exposure in these facilities. This study investigated the determinants of airborne endotoxin exposure in dental health care settings. There was a two-fold variation in personal airborne endotoxin from the least exposed (administration) to the most exposed (laboratory) jobs (geometric mean levels: 2.38 vs 5.63 EU/m3). Three percent of personal samples were above the DECOS recommended exposure limit (50 EU/m3). In the univariate linear models, the age of the dental units explained the most variability observed in the personal air samples (r2 = 0.20, p<0.001), followed by season of the year (r2 = 0.11, p<0.001). Other variables such as institution and total number of dental units per institution also explained a modest degree of variability. In conclusion, this study identified several workplace determinants that predict endotoxin exposure in dental settings such as job type and dental unit characteristics.
Full Text Available